Magnetic core deca-flip



Filed May 3, 1954 IDEAL ACTUAL FIG.

I ndu FIG. 2

imh CHOKE m mm Em m W E m m N s m V 5 7 I B F V V V 0 0 O m w z United States Patent Ofiice 3,lh2,'lhli Patented Dec. 222, 1964 This invention relates to a trigger or flip-flop circuit in which the usual electron tubes are replaced in part by a magnetic element which is capable of assuming more than two stable magnetic states.

In general, the conventional trigger circuit includes two discharge tubes so interconnected that when either tube is conductive, the other is cut oil. The trigger circuit will remain in either of these two stable states until a controlling pulse is applied to reverse the conducting status of the tubes. Voltage values at points in the trigger circuit differ according to whether the tubes are in one relative conducting status or the other, and such voltage variations may be used for diverse binary storage or circuit controlling purposes as is well known. In such prior art electronic devices, with the grids of th two tubes coupled together, the flip-flop unit is caused to turn over once on application of each controlling input pulse. When a succession of such pulses are applied, the trigger alternates baclr and forth between the two stable states. A trigger unit connected in this manner is bistable and may be used as a binary counter as is well known.

in accordance with the invention a multi-stable device is provided wherein a plurality of input pulses are applied in succession to cause the unit to turn over once. Application of plural groups of pulses, therefore, are required to cause the device to alternate back and forth between two limiting states.

ilre other systems employing magnetic materials for storage and handling information, the advantage of reliability is inherently prescnt in the device comprising the invention, and in addition, a high storage capacity is provided with respect to the space occupied and the number of elements of which it is composed.

One object of the invention, therefore, is to provide a fiip-llop device having high storage capacity.

Another object is to provide a trigger circuit in which the status is altered in response to application of a predetermined number of input pulses.

Still another object is to provide a trigger circuit employing a magnetic element in which the triggering action is initiated by incremental changes in flux density of the magnetic element.

A further object is to provide a trigger circuit in which the status is altered by initiation of incremental changes in the permeability of a magnetic element.

A further object is to provide a magnetic trigger circuit capable of operation as a counting device.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

in the drawings:

FlGURE 1 is a diagrammatic representation of the actual and ideal hysteresis curve for magnetic materials such as that employed in the trigger circuit.

FIGURE 2 is a schematic diagram illustrating the decafiip or multi-stage lip-flop device.

FIGURE 3 is a diagram of the wave forms of pulses appearing at various points in the circuit of FXGURE 2.

Magnetic material having the property of low coercive force and high residual magnetism may be readily mag netized in one direction or one remanence state representative of a binary one and in the opposite remanence Cir state representative of a binary zero. A core fabricated of such materials may be placed in one of these two limiting states of remanence by means of windings on the core to which pulses are applied, and the particular state existing may be determined by a voltage pulse induced in other windings on the core when the flux state is reversed. [in ideal core material for this purpose would have a substantially rectangular hysteresis loop such as that illustrated by the solid line curve in FIG- URE 1.

With a core of such material initially at a remanence state represented as point a on the hysteresis curve, application of a positive magnetizing force ]-I'l, sulfioiently greater than the coercive force, will cause the core to traverse the loop to saturation point b and, on removal of the applied magnetomotive force, returns to remanence point c. Similarly, when at a state represented by point 0, application of a negative magnetizing force *l-l, sufiicientiy greater than the coercive force, causes the core to traverse its hysteresis curve from point c to saturation point ri" and, on removal of the force goes to remanence point a. The change in flux in going frompoint a to point 0 or from point c induces an output voltage in each of the windings on the core, however, application of a magnetomotive force tending to maintain the core in either limiting remanence state would ideally produce no change and consequently no output pulse would produced. Due to the fact that core materials do not possess perfectly rectangular hysteresis loops but are more nearly as illustrated in dotted lines in the figure, there is a change, for example, as when the core goes from its stable negative remanence state a to its negative saturation state [1 on application of a force of -H and a voltage of reduced magnitude is induced in the secondary windings.

lvlagnetic materials having a more nearly rectangular hysteresis characteristic are employed in the present invention and in the description to follow, the coercive force is considered to approximate a sharply defined constant under all conditions of magnetization and the saturation flux density then is sharply defined under all conditions of magnetizing force. The magnetic state of the ideal material is constant under the influence of magnetic forces less than the coercive force and, when exceeded slightly, the flux density will change at a rate determined by the electromotive force applied to the winding. The total change in tlux density over a given time interval will be directly proportional to the integral of the applied electromotive force over the same time interval provided saturation is not reached and losses in the winding neglected.

it has been determined that the electromotive force need not be continuously applied during the aforementioned time interval but may be applied in the form of pulses with the total change in flux density being directly proportional to the numbe, magnitude and duration of the individual pulses. Maintaining the magnitude and duration of the pulses constant; therefore, a predeten mined number of pulses are required to efiect a change in the magnetic state of the core material. Such pulses are termed quantified impulses and the number required to cause a predetermined change in flux density then dc pends upon the ability of associated apparatus to accurately quantify the pulses applied and to detect the changes produced by them in the core and windings. Such a magnetic core may have a plurality of stable states intermediate the upper and lower saturation limits and may be employed, therefore, to store other than merely binary representations.

Referring to FIGURE 1, n quantified impulses applied to a helix inductively embracing the material are required to cause a change in flux density in going from point a to point c on the hysteresis curve. Point a LO point a therefore may be taken as representing a zero or datum point. Ideally, this limiting state would be complete magnetic saturation of the core in one direction, however, with practical materials available the remanence state a is somewhat less than complete saturation. Each pulse applied to a helix on the core causes a net change in the magnetic state directly proportional to the integral of the applied pulse and the magnetization is moved in the direction of saturation opposite to the limiting state of the datum point. A pulse designated as the nth pulse will produce dynamic saturation of the core in the sense opposite to that produced initially and further pulses applied will no longer produce a significant flux change since the only change possible is the relatively small 1ncrement or": change in going from the static remanence state to dynamic saturation b. At this time no significant output pulse will be developed in secondary windings on the core and this indicates that a limiting state has been reached.

By varying the polarity of the applied quantified input pulses, the processes of both addition and subtraction may be performed within the core and the algebraic sum of the pulses applied may be determined by continuing to magnetize the memory element away from or down to the previously defined datum state. In continuing to magnetize the core in the same sense, the number of pulses required to reach the opposite saturation limit is the complement of the number stored, while magnetizing the core in the opposite sense to return it to the datum point will require a number of read out pulses equal to the true number accumulated.

In the embodiment illustrated in FIGURE 2, a magnetic flip-flop is depicted which requires 11 quantified input pulses for changing the voltage levels at points in the network designated as output terminals and the groups of n pulses are employed to drive the core alter" ately betweenthe upper and lower static limiting remanence states.

The core 16 is shown as having two similar windings Jill and 12 with one terminal of each winding being commonly connected at 13 to a pulse transformer 14 and a pulse forming network generally designated as 315. The other terminals 16 and 1'7 of the windings it and 12; are connected to ground through a diode D1 and vacuum tube V1 and a diode D2; and vacuum tube V2, respectively. The tubes V1 and V2 are shown as separate tube elements, however, they may be incorporated in a single envelope as in the actual circuit developed. A resistor bridge network comprising two paralleled branches of three resistors labeled l8, 1%, 2d and 21, 2,2, 23 and having values of K ohms, 11K ohms and 4.71%. ohms, respectively, in the order listed, is connected between terminals 24 and 25, to which voltages of +300 volts and 75 volts are applied. The connection point 26 between the plate of tube V1 and cathode of diode Dlt is coupled to the junction of resistors 18 and 19 of one branch of the resistor bridge and the grid of the tube V1 is connected at a point 27 tothe junction of the resistors 22 and 23 of the other branch. Similarly, the connection at point 23 between the plate of tube V2 and cathode of diode D2 is connected to the junction of resistors 21 and 22 of the other branch of the resistor bridge and the grid of the tube V2 is connected at a point 29 to the junction of the resistors 19 and 25B of the first branch. The aforementioned pulse transformer ltd comprises a core having three windings 39, 252i and 32. The output winding 32 is grounded at one terminal and the other terminal is connected to the common junction 13 of windings 11 and 12 of the multistage core Til. Winding 31 is connected at one end to a terminal to which a positive potential of +300 volts is applied and the other end of the winding is connected to the plates of a pair of vacuum tubes V3 and d, the cathodes of which are grounded as shown. Winding 3b of the pulse transformer 14 is connected to a terminal 35 to which a bias voltage of 55 volts is applied through a variable condenser LC circuit and the grid of tube V4 is connected to one terminal of the winding 3%). The grid of the tube V3 is connected to an input terminal 37 and is biased to 20 volts by connection through a paralleled diode 3 and 22K ohm resistor 3d. Tube V4 functions as a single swing blocking oscillator and is normally in a non-conductive state with the grid biased sufiiciently negative by the 55 volt source to hold the tube cut oil. Tube V3 is also normally non-conductive, however, as an input pulse of positive polarity is applied to its grid, current flows through the winding 31 and tube V3 to ground. A positive voltage is developed at the lower terminal of winding 38 and is applied to the grid of tube V4 and the latter remains conductive until the reflected pulse returns. The initial conduction of tube V3 also induces a positive voltage pulse in Winding 32 and determines the leading edge thereof while the duration of timing of the trailing edge is determined by the time of cutoff of tube V4.

initial conditions are established by pulsing the core it? to saturation in one direction or datum point. Subsequent pulses tend to move the flux in the opposite sense, and as the first quantified pulse appears in winding 32 of ulse transformer 1 and is applied to the flip-flop unit, principal current path is followed from the junction 13 of windings l1 and 1 2. through winding ll, diode D1 to the terminal 26 and thence in parallel through the resistors 19 and 2% of the first branch of the resistor bridge to the v. bias source and also at terminal 26 through the tube V1 to ground. This current moves flux in the core and the winding 12. then functions as an autotransforiner to develop a pulse of approximately twice the amplitude of the quantified driving pulse. Diode D2 conducts only when the pulse is above a value approximately equal to the amplitude of the quantified pulse and the current in the path including diode D2 is significantly less than hat in the path including the diode D1 because the associated tube V2 is cut off and the current is attenuated by the resistors 22 and 23 comprising a portion of the other branch of the resistor bridge.

After application 01"" 12 pulses, the core it? reaches a saturated state opposite to that initially present so that the impedance of winding lll is reduced to the resistance value of the winding and essentially no flux is moved. The voltage at point 26 then rises to approximately the magnitude of the input pulse while the voltage at point lowers, since the auto-transformer effect is lost when no further flux is moved in the core. The combined effects of the voltage change at points 26 and 28 operate through the resistors 19 and 22 to out Oh tube V1 and to initiate conduction in tube V2. Output leads may be connected to the terminals 26 and 28 and are subjected to a significant change in voltage upon the receipt of is input pulses. Reversing the conductive status of tubes V1 and V2 in this manner sets up the circuit to drive the core in in the opposite magnetic sense and the (n+1)th pulse fiows through winding 12, tube D2 to terminal 2-3 and thence in parallel through the 11K and 4.7K resistors and 23 of the other branch and through the now conducting tube V2 to ground. During the application of pulses numbered (n+1) to (2b), the winding 11 acts as an auto-transformer until saturation in the initial direction is again reached and the impedance of winding 12 is reduced to that of the resistance. The voltage at point 25 then lowers to the approximate value of the quantified input pulse as the auto-transformer action fails and the tube V2 cuts off while point 23 rises in potential and the grid of tube Vi, which is connected to this terminal through the 11K resistor 22 of the second branch, is raised in potential to render tube V1 conductive. Sucessive application of groups of n pulses cause the output terminals 26 and 28 to be alternately raised and lowered in potential as the tubes V1 and V2 are a1tcrnately rendered conductive and non-conductive.

In actual practice, the windings ill and 12 are formed of 3G0 turns. each and input pulses of approximately 25 volts positive and 0.25 microsecond duration are employed. The variable capacitors of the network 15 are adjusted so that ten pulses are required to saturate the core in either direction so that a device operable in the decimal system is provided. With these circuit values and the values of the resistors ill-23 previously given, the voltage levels at various points in the circuit with respect to ground are indicated in PlGURlE 3 with the tube Vil conductive and tube V2 non-conductive.

From this iigure it will be observed that the quantified pulse applied at terminal 13 is approximately 209 volts and is attenuated at llti by the drop throu h winding ll, which acting as the primary of the auto-transformer at this time, and output terminal 26 is subjected to a voltage of +60 volts. Terminal i) of winding 12 is functioning as the secondary of the auto-transformer and the voltage to ground is approximately 400 volts. terminal 28 is subjected to a voltage of approiimately +200 v. as the diode D2 conducts only when the pulse is above 200 volts, and consequently the potential is reduced to about half that of terminal 17. it is thus seen that a voltage differential of sulficient magnitude is obtained at the output terminals to control other apparatus.

As previously mentioned in connection with multi-state cores generally, addition and subtraction can be performed within the core by driving it in incremental steps in one or the other direction of dynamic saturation. The multistage or deca-fiip trigger unit here described is also capable of subtraction and addition in a similar manner. A number of pulses to be accumulated are applied to the input terminal 37 and with each multiple of n impulses applied an output is al ernately obtained at terminals 26 and With a number less than 11 standing in the flipilop, that is with 111 pulses having been applied and the core llll driven away from the datum magnetic state by m increments, then subtraction of a number may be performed by application of signals to the grids of tubes V1 and J2 to reverse their conductive status and a number of identical pulses applied to junction 13 equal to the value of the negative number. This drives the core it back toward the reference datum and after completion of the negative entry the status of tubes V1 and V2 may be reversed again and the accumulation of positive values continued.

it is further contemplated that the core ltl may be driven in only one direction of saturation in accumulating 1 impulse representations in that it is unnecessary to drive the core in incremental steps first toward one and then toward the other limiting magnetic state. With the core initially placed in one remanence state as a datum point, quantified input pulses drive the core toward the opposite remanence state and on application of the nth pulse the voltage level of output terminal 26 or 23 undergoes a significant change. This output may be employed to reset the core i to the initial datum point in one step and need not be quantified provided it is at least sufficient to exceed the coercive force of the material. The (n+l)th pulse then retraces the conditions produced by the first quantified pulse and the output from the nth pulse may further be used to provide an input for another of a group of cascade connected trigger units employed to accumulate successive orders of a multidigit number.

It is to be specifically understood that while particular means for controlling and quantifying the input pulses applied to the multi-state fiipdlop has been illustrated, the invention is not to be considered limited to any specific means and that any apparatus operable to perform such functions may be employed.

W tile there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the rorm and details of the device illustrated and in its 3 operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

l. A flip-flop circuit comprising a magnetizable element capable of assuming a multiplicity of stable magnetic states between two limits, means including a source of discrete unidirectional digit representing electrical impulses and a pair of windings inductively associated with said element for magnetizing said element in step by step fashion in one direction from one of said limits and thereafter in a reverse direction from the other of said limits, at discharge device connected in series with each of said windings, and output means coupled to said discharge devices for producing an indication at the time said magnetizable element reaches one of said limiting states.

2. A flip-flop circuit of the character described comprising a magnetic element, a source or" discrete unidirectional digit representing electrical impulses of uniform character, means for magnetizing said element toward a limiting magnetic state of one polarity and thereafter toward a limiting state of opposite polarity in discrete steps in response to application of said electrical impulses, and means coupled with said flip-hop circuit for producing an indication on attainment of either of said limiting states.

3. A flip-flop circuit compdsing a magnetizable element capable of successively assuming anyone of a plurality of stable magnetic states between two limits, input circuit means coupled with said element and adapted to be subjected to a series of unidirectional electrical impulses of uniform character, means for causing said element to assume successive ones of said stable magnetic states toward one of said limits and thereafter toward the other of said limits in response to successive application of a plurality of said impulses, and means connected with said flip-flop circuit for producing an indication on attainment of either of said limits.

4. A frequency divider circuit comprising a magnetizable element capable of assuming a plurality of stable ma gnetic states between two limits, a pair of windings inductively associated with said element, a discharge device connected in series with each of said windings, input means coupled with said windings and adapted to be subjected to a series of unidirectional electrical impulses of uniform character whereby said element is caused to assume successive ones of said stable magnetic states toward one of said limits and thereafter toward the other of said limits step by step fashion, and output circuit means coupled with said discharge devices for producing an indication on attainment of either of said limits.

5. A flip-flop circuit having two sustained states of equilibrium and comprising a single ferromagnetic core, a pair of windings on said core, means supplying unidirectional electrical impulses of uniform character to said windings whereby said core is magnetized to successive stable magnetic states in one direction toward a first limit and thereafter in successive stable magnetic states toward a second l'mit with said flip-flop circuit remaining in one of said sustained states of equilibrium during the period that said core is magnetized toward one of said limits and in the other of said two sustained states of equ librium during the period that said core is magnetized toward the other of said limits.

6. A trigger circuit having two states of equilibrium comprising a magnetic core, a pair of windings on said core, means supplying a series of unidirectional electrical impul es of uniform character to said windings, means in series with each of said windings and controlled by electrical conditions developed in the other of said windings, the impedance of one of said windings being varied in response to application of a predetermined number of said s eaves i7 alternate states of equilibrium in said trigger circuit in response to application of groups of predetermined numbers of said impulses.

7. A flipd'lop circuit capable of being reversed from one state of equilibrium to the other comprising a core, inductively associated windings on said core, means supplying a series of unidirectional electrical impulses of like character to said windings, a unidirectional conducting device in series with each of said windings, an electronic switch device in series with each of said windings, means biasing said switch devices to cut off, means controlling the conductive status of said switch devices in response to voltages developed in the other one of said windings.

8. A memory trigger comprising a magnetizable core capable of assuming a plurality of stable magnetic states between two limits, a pair of windings on said core, means supplying electrical impulses or like character representing digital values to said windings to thereby change the magnetization of said core in discrete steps from one limit toward the other, said windings alternately functioning as primary and secondary windings of an autotransformer in response to application of a predetermined number of said impulses to thereby establish two states of equilibrium in said trigger, and circuit means coupled with said windings for producing an indication as alternate ones of said states of equilibrium are established.

9. In a memory sy -em flip-lop having two stable states of equilibrium, a magnetizable element having a substantially rectangular hysteresis characteristic and capable of assuming two stable states of magnetism of opposite polarities as well as a multiplicity of intermediate stable states between said two stable states of opposite polarities, input means for adding a number of discrete magnetizing pulses to said element to thereby change its magnetization from a limiting state of one polarity toward a limiting state of opposite polarity and a second number of magnetizing pulses to change its magnetization from the limiting state of opposite polarity toward the limiting state of said first polarity, means coupled to said element for producing an indication only on reaching one of said limits.

10. In a memory system flip-flop having two stable states of equilibrium, a magnetizable element having a substantially rectangular hysteresis characteristic and capable of assuming a multiplicity of stable states intermediate two limit, a source of electrical impulses of uniform character, means inductively associated with said element and coupled to said source whereby said element is caused to be magnetized step by step in one direction toward a first limit in response to impulses representative of positive values up to a predetermined number and thereafter in a reverse direction up to a predetermined number while said element is caused to be magnetized step by step in a contrary direction in representing negative values, and means coupled with said inductively associated means for producing an indication only When said element reaches one of said two limits.

11. A flip-flop circuit comprising a magnetizable element capable of assuming a multiplicity of stable magnetic states between two limits, a source of discrete unidirectional digit representing quantified impulses, input circuit means including a pair of windings for applying said quantified impulses to said magnetizable element to thereby magnetize said element in step by step fashion in one direction from one of said limits and thereafter a reverse direction from the other of said limits, a discharge device connected in series with each of said windings, and output circuit means coupled to said windings and adapted to alternately attain one of two voltage levels in response to application of a predetermined plurality of said impulses.

12. A trigger circuit having two states of equilibrium comprisin a'single ferromagnetic core, first and second windings on said core, means supplying unidirectional electrical impulses of uniform character to said windings, first and second electron discharge devices in series with said first and second windings, respectively, each of said discharge devices being controlled by voltages developed in the winding connected in series with the other discharge device, and means for causing said discharge devices to be alternately conductive in response to application of a predetermined number of said impulses to said windings to thereby establish alternate stable states of equilibrium in said trigger circuit.

13. A trigger circuit comprising a magnetic core hav ing a pair of inductively associated windings, means supplying a series of electrical impulses of like character to said windings, and first and second means for controlling the current in said windings and each connected in series with a corresponding one of said windings and controllable by the impedance developed in the other of said windings, the impedance developed in said windings being caused to vary in response to application of a predetermined number of said impulses.

14. A magnetic circuit comprising a magnetizable element capable of assuming a multiplicity of stable magnetic states between two limits; first and second windings inductively associated with said element; means for applying a series of discrete pulses; and first and second means connected to said first and second windings, respectively, each for controlling the current in the connected winding when one of said pulses is applied; said first and second means being coupled to said second and first windings, respectively, and each being controllable by the impedance of the coupled winding; whereby each of said pulses renders one of said windings efiective to apply a quantified magnetizing impulse to said core and said core is magnetized in step by step fashion between said limits in response to said pulses.

15. A device of the class described comprising a saturable core having a winding thereon, said core being composed of such a material that its flux density may be successively increased in step by step fashion in response to a series of spaced current pules through said winding, input means for reverting the core to a given point on its hysteresis loop in response to given input conditions, and output means responsive to the potential developed across said winding.

16. A device of the class described comprising a saturable core having a winding thereon, said core being composed of such a material that its flux density may be successively increased in step by step fashion in response to a series of spaced current pulses passing through said winding, an input, means which in response to predetermined conditions at said input causes successive current pulses to pass through the winding to raise the flux density of the core by one step in response to each said pulse until after a predetermined plurality of pulses the core reaches saturation, and output means controlled by whether or not the core is saturated, each step being a fraction, not greater than one-half, of the flux density required to saturate the core.

17. A device of the class described comprising an input, a source of spaced pulses, means for producing a series of output pulses spaced the same as the first-named pulses in reponse to a predetermined condition at said input, the last-named means including a saturable core of a type whose flux density may be increased in step by step fashion in response to spaced surges of magnetizing force applied thereto and a winding on said core through which pulses from said source pass to increase the flux density of the core in said step by step fashion, and output means controlled by the impedance of said winding, the size and material of the core being so related to the winding, the amplitude of the current and the spacing of the pulses that a plurality of said pulses must flow through the winding before the flux density of the core is increased in step by step fashion to a sutlicient extent to saturate the core.

18. A device of the class described comprising a source for successively energizing of spaced power pulses, a saturable core composed of a material whose flux density may be increased in step by step fashion in response to spaced surges ot magnetizing force applied thereto, an output, means for increasing the flux density in said core along an unsaturated portion of its hysteresis loop in response to each said power pulse and which after a predetermined number of power pulses saturates the core, and means controlling the current in the output in accordance with whether or not the core is saturated.

19. A delay flop as defined in claim 18 including input means for resetting the core to a given point on its hysteresis loop in response to predetermined input conditions.

20. A delay flop as defined in claim 18 which is resettable comprising input means for at any time resetting the core to a given point on its hysteresis loop in response to predetermined input conditions.

21. A delay flop comprising a transformer having a saturable core composed of such material that the flux density thereof may be successively increased in step by step fashion in response to a series of spaced surges of magnetizing force, mean including a primary winding on the core for resetting it to a given point on its hysteresis loop in response to an input pulse, a source of spaced pulses, a secondary winding on said core for receiving pulses from said source, the spacing and amplitude of the pulses being so related to the core material and the secondary winding that it requires a plurality of said pulses to increase the fiux density in step by step fashion to saturation, and output means controlled by the impedance of said secondary winding.

22. A device of the class described comprising a saturable core having a winding thereon, said core being composed of a material having a substantially rectangular hysteresis loop and whose flux density may be changed in step by step fashion in response to space surges of magnetizing force applied thereto, input means for reverting the core to a given point on its hysteresis loop in response to given input conditions, a source of spaced power pulses said Winding with pulses of such small magnitude that one pulse will not alone drive the core to saturation, whereby a predetermined number of pulses are required before the core reaches saturation, and output means responsive to the potential developed across said winding.

23. A delay fiop comprising a source of spaced power pulses, a saturable core having a substantially rectangular hysteresis loop and whose iiux density may be changed in step by step fashion in response to spaced surges of magnetizing force applied thereto, an output, means for increasing the flux density in said core along a vertical portion of its hysteresis loop a distance not greater than half that required to reach a horizontal portion of the loop in response to each said power pulse and which after a predetermined number of power pulses saturates the core, and means controlling the current in the output in accordance with whether or not the core is saturated.

24. A control circuit comprising a translating means having an input and an output, a source of pulses, means selectively coupling said source of pulses to said input, said last-named means including variable impedance means having first and second distinct magnitudes, said impedance means comprising a core of magnetic material having a first coil thereon, one end of said first coil being coupled to said source of pulses and the other end of said first coil being coupled to the input of said translating means, the saturation state of said core being changed in response to application of a predetermined number of pulses from said source to said coil for changing the impedance of said first coil from said first to said second magnitude, thereby to pass a predetermined signal from said source of pulses via said first coil to the input of said translating means, and means for selectively causing said 10 impedance means to change from said second to said first magnitude, said last-named means comprising a second coil carried by said core and having one end thereof coupled to the output of said translating means.

25. A counter circuit comprising a translating means producing an output in response to an input thereto, a source of input pulses to be counted, variable impedance means coupling said source of pulses to the input of said translating means, said impedance means comprising a core of magnetic material having a coil thereon, one end of said coil being coupled to said source and the other end of said coil being coupled to the input of said translating means, potential clamp means coupled to said other end of said coil for normally maintaining said other end of said coil and the input of said translating means at a predetermined potential, the saturation state of said core being changed in response to applications of a predetermined number of pulses from said source to said coil for changing the impedance of said coil from a high impedance value to a low impedance value, whereby a pulse from said source passes via said coil when the impedance of said coil changes to said low value thereby to change the input potential of said translating means from said clamped predetermined potential.

26. A scale of N counter comprising a translating means having an input, a source of pulses to be counted, a selectively saturable magnetic circuit coupling said source of pulses to said translating means input,'said magnetic circuit comprising a core of magnetic material exhibiting a substantially rectangular hysteresis loop and having a coil thereon, one end of said coil being connected to said source and the other end of said coil being connected to the input of said translating means whereby said magnetic circuit is responsive to a succession of N pulses applied to said coil from said source for changing said core from an unsaturated to a saturated condition, thereby to pass every Nth pulse from said source of pulses via said coil to said translating means input, and reverting means responsive to an output from said translating means for changing said core to an unsaturated condition subsequent to the passing of a pulse via said coil to said translating means input.

27; A counter circuit comprising: a source of pulses to be counted, a core of selectively saturable magnetic material exhibiting a substantially rectangular hysteresis loop, said core being responsive to a predetermined plurality N of pulses from said source for causing said core to change from a substantially unsaturated to a substantially saturated condition, a coil carried by said core and having one end thereof coupled to said source, and output means coupled to the other end of said coil, whereby the Nth pulse from said source passes through said coil to said output means when said core assumes a saturated condition.

28. A counter as set forth in claim 27 further including means for causing said core to revert to a substantially unsaturated condition subsequent to the passage of said pulse through said coil to said output means.

29. A counter as set forth in claim 28 wherein said reverting means is a magnetomotive force means.

References titted in the file of this patent UNITED STATES PATENTS 1,110,550 Hewitt Sept. 15, 1914 1,975,164 Ludwig Qct. 2, 1934 2,300,539 Faulk Nov. 3, 1942 2,430,457 Dimond Nov. 11, 1947 2,591,406 Carter et a1 Apr. 1, 1952 2,682,615 Szihlai et a1 June 29, 1954 2,742,567 Hansell Apr. 17, 1956 2,757,297 Evans et a1 July 31, 1956 2,772,370 Bruce et al Nov. 27, 1956 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,162,768 December 22, 1964 Tenny Lode It is hereby certified that'error appears in the above numbered patent requiring correction and that the said Letters, Patent should read as corrected below.

Column 8, line 58, beginning with "17. A device of" strike out all to and including "saturate the core." in line 74, same column 8; column 9, line ll, beginning with "19.. A delay flop" strike out all to and including "across said winding." in line 45, same column 9; column 8, line 75, for "18." read l7. column 9, line 46, for "23." read l8, line 59, for "24." read l9. column 10, line 5, for "25." read 20. line 25, for "26." read Zl. line 43, for "27." read 22. line 55, for "28." read 23. same line 55, for the claim reference numeral "27" read 22 same column 10, line 59, for "29." read 24. same line 59, for the claim reference numeral "28" read 23 in the heading to the printed specification, line 7, for "29 Claims" read 24 Claims Signed and sealed this 3rd day of August 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,162,768 December 22, 1964 Tenny Lode It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 8, line 58, beginning with "17. A device of" strike out all to and including "saturate the core." in line 74, same column 8; column 9, line 11, beginning with "19. A delay flop" strike out all to and including ."across said winding."

in line 45, same column 9; column 8, line 75, for "18." read l7. column 9, line 46, for "23." read l8. line 59, for "24." read l9. column 10, line 5, for "25." read 20. line 25, for "26." read 21. line 43, for

"27." read 22. line 55, for "28." read 25. same line 55, for the claim reference numeral "27" read 22 same column 10, line 59, for "29." read 24. same line 59, for the claim reference numeral "28" read 23 in the heading to the printed specification, line 7, for "29 Claims" read 24 Claims Signed and sealed this 3rd day of August 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

25. A COUNTER CIRCUIT COMPRISING A TRANSLATING MEANS PRODUCING AN OUTPUT IN RESPONSE TO AN INPUT THERETO, A SOURCE OF INPUT PULSES TO BE COUNTED, VARIABLE IMPEDANCE MEANS COUPLING SAID SOURCE OF PULSES TO THE INPUT OF SAID TRANSLATING MEANS, SAID IMPEDANCE MEANS COMPRISING A CORE OF MAGNETIC MATERIAL HAVING A COIL THEREON, ONE END OF SAID COIL BEING COUPLED TO SAID SOURCE AND THE OTHER END OF SAID COIL BEING COUPLED TO THE INPUT OF SAID TRANSLATING MEANS, POTENTIAL CLAMP MEANS COUPLED TO SAID OTHER END OF SAID COIL FOR NORMALLY MAINTAINING SAID OTHER END OF SAID COIL AND THE INPUT OF SAID TRANSLATING MEANS AT A PREDETERMINED POTENTIAL, THE SATURATION STATE OF SAID CORE BEING CHANGED IN RESPONSE TO APPLICATIONS OF A PREDETERMINED NUMBER OF PULSES FROM SAID SOURCE TO SAID COIL FOR CHANGING THE IMPEDANCE OF SAID COIL FROM A HIGH IMPEDANCE VALUE TO A LOW IMPEDANCE VALUE, WHEREBY A PULSE FROM SAID SOURCE PASSES VIA SAID COIL WHEN THE IMPEDANCE OF SAID COIL CHANGES TO SAID LOW VALUE THEREBY TO CHANGE THE INPUT POTENTIAL OF SAID TRANSLATING MEANS FROM SAID CLAMPED PREDETERMINED POTENTIAL. 